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extrema.m, extrema2.m

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14 Sep 2006 (Updated )

Search all extrema points of a time series or a surface with/without NaN's.

Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

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File Information
Description

Search all the maxima and minima points (peaks) in a time series (vector) or a surface (matrix), via columns, rows and crossing diagonals, ignoring NaN's elements.

USAGE:

[zmax,imax,zmin,imin]= extrema2(peaks);

where zmax (zmin) are the maxima (minima) elements and imax (imin) their linear index (check IND2SUB).

They come with the examples on the screenshot.

These are the same files as EXTREME.M and EXTREME2.M, but updated.

Acknowledgements

This file inspired Bi Dimensional Emperical Mode Decomposition (Bemd), Find Depressions, Telo Tool Terminal Restriction Fragment Analysis, Minima Maxima3 D, Extrema, and Find Extrema.

MATLAB release MATLAB 7 (R14)
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Comments and Ratings (35)
25 Nov 2014 Zohar Bar-Yehuda

Simple and useful.

16 Oct 2014 Phillip

Using this across a broad range of applications, very handy.

17 Sep 2014 Shuangshi  
16 Sep 2014 sara

how can I use this mfile to run over my image?

09 Jul 2014 karlosgk  
24 Mar 2014 Hugo

Thx, works great!

11 Mar 2014 Vincent

thank you
this saves me a day of coding...

27 Jun 2013 Shirah

Hello, does anybody know how to replicate those detected extrema points onto a grayscale image.

Thank You

10 Apr 2013 Rafael Freire

Do you have an option to put the sensitivity of the peaks? to only get the higher ones....

21 Mar 2013 Kumar  
29 Jun 2012 M@lik Ali

Hi all i have to calculate the LUV color components any one can help me...
Thanks in Advance..

30 Apr 2012 Camille Couzi

Hola Carlos!
Thanks for your contribution.
I am having some issues though... I am using your function inside a script which uses fminsearch also... and getting the following error message:

Maximum recursion limit of 500 reached. Use set(0,'RecursionLimit',N)
to change the limit. Be aware that exceeding your available stack space can
crash MATLAB and/or your computer.

Error in extrema

Error while evaluating uicontrol Callback

Help! How do I solve this problem!
Gracias y muchos saludos!

22 Mar 2012 raj

{surf(T,f,G'), shading interp
[Gmax,imax,Gmin,imin] = extrema2(G);
hold on
plot3(T(imax),f(imax),Gmax,'bo')
for i = 1:length(Gmax)
text(x(imax(i)),y(imax(i)),zmax(i),[' ' num2str(zmax(i))])
end
hold off}
My problem is the T,f,G are of different sizes and an error comes up saying '??? Index exceeds matrix dimensions.' any suggestions please help

22 Mar 2012 raj

I have a problem while using it for an array can u explain an example as u did it for a vector please, I am a begginer with this stuff

04 Mar 2012 Luke Winslow  
04 Mar 2012 Luke Winslow  
14 Feb 2012 Anusha

Can someone help me on how to adapt this to detect maxima and minima points on an object edge?

12 Dec 2011 Thomas

much better than findpeaks for my data thanks so much!

30 Oct 2011 Onkar Singh Gujral  
25 Aug 2011 Aslak Grinsted

Nice. There is also the built-in function findpeaks from the signal processing toolbox:

http://www.mathworks.se/help/toolbox/signal/findpeaks.html

29 Apr 2011 Rafael Freire

Perfect for finds maximun and minimuns in a surface! Great Job

15 Feb 2011 Rick Towler

Nice work.

15 Feb 2011 Rick Towler  
26 Mar 2010 Sanjeev

Excellent work

28 May 2009 joe saucer

hey guys.. is their anyway for this program to just give me the biggest maxes? my plot has many, many small peaks.. also, can you store these as variables?

14 Nov 2008 Yin Wang

Excellent work, this is exactly what I need.

12 Jul 2008 angeles sierra

kiero agregar un linck a mi fotolog
pero no se como aserle

09 Apr 2007 Carlos Adrián Vargas Aguilera

You are so right Dimitri! I've made a terrible translation from spanish, I meant "extrema points"... Ouch! I need to change even the name!

06 Apr 2007 Dimitri Shvorob

It might be helpful to briefly explain the exact definition of 'extreme points'.

01 Mar 2007 Jacob Eisenstein

thanks, very helpful.

15 Jan 2007 Johnny Job

Well done.

22 Nov 2006 Carlos Adrián Vargas Aguilera

Thanks JaeKyu Suhr!, new file with bug fixed in about 1 day...

22 Nov 2006 JaeKyu Suhr

This is excellent, but when i use extreme2.m
There is an error related to a variable "indx".
Therefore, I put a little bit of code in "extreme.m" like this

% NaN's:
inan = find(isnan(x));
if ~isempty(inan)
indx = 1:Nt;
indx(inan) = [];
x(inan) = [];
Nt = length(x);
%%----added code
else
indx = 1:Nt;
%%%%%%%%%%%%%%%%
end

14 Nov 2006 cloves souza

e muito legal

15 Sep 2006 Sasha Trevizo

The author sure had a headache after he finished this, so, thanks for avoid it to me! It works really good!

Updates
13 Nov 2006

English translation from spanish. Little changes on the submit and screenshot.

17 Nov 2006

Now accepting NaN's.

22 Nov 2006

Fix bug in indx (by JaeKyu Suhr)

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